Sky-Watcher Dob 18" (458/1900) Truss Tube Telescope
Newtonian reflector. Aperture: 114mm. Focal length: 900mm
Sky-Watcher Dobsonians with their huge light gathering capabilities provide the ultimate WOW factor experience for aficionados of visual astronomy. The elegant and rigid all metal truss tube design is easily transportable when unassembled, and can be assembled and ready for use in less than 20 minutes. The mount provides smooth manual operation in both alt and azimuth axes. Delivers outstanding performance on planetary and deep-sky objects.
The telescope features high quality parabolic primary mirrors to eliminate spherical aberrations inherent in 'fast' focal lengh reflectors with spherical primary mirrors. The mirrors are parabolized to bring all the light rays to the same focal point to give sharp, constrasty images, which are full of detail.
Most reflectors today usually have a coat of aluminum as the mirror surface and then an overcoat of silicon monoxide or silicon dioxide to protect it. Silicon dioxide produces a much more durable coat than silicon monoxide but requires specialized equipment to apply it and is therefore more expensive. Protection is needed, because in most reflectors, the mirror is open to the elements and deterioration of the reflective layer reduces the resolution of the telescope. All Sky-Watcher reflectors are multi-coated with silicon dioxide as standard for optimum durability and long term performance.